Friday, August 17, 2012

Tackle It Tuesday Preview Aurora Borealis

Dear Haijin,

A new Tackle It Tuesday Preview for next week's theme. Next week's theme is Aurora Borealis or The Northernlight as seen on the Northpole and Southpole (than called Aurora Australis or The Southernlight)

The Northernlight or Aurora Borealis
An aurora (plural: aurorae or auroras; from the Latin word aurora, "sunrise") is a natural light display in the sky particularly in the high latitude (Arctic and Antarctic) regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere (thermosphere). The charged particles originate in the magnetosphere and solar wind and, on Earth, are directed by the Earth's magnetic field into the atmosphere. Aurora is classified as diffuse or discrete aurora. Most aurorae occur in a band known as the auroral zone, which is typically 3° to 6° in latitudinal extent and at all local times or longitudes. The auroral zone is typically 10° to 20° from the magnetic pole defined by the axis of the Earth's magnetic dipole. During a geomagnetic storm, the auroral zone will expand to lower latitudes. The diffuse aurora is a featureless glow in the sky which may not be visible to the naked eye even on a dark night and defines the extent of the auroral zone. The discrete aurorae are sharply defined features within the diffuse aurora which vary in brightness from just barely visible to the naked eye to bright enough to read a newspaper at night. Discrete aurorae are usually observed only in the night sky because they are not as bright as the sunlit sky. Aurorae occasionally occur poleward of the auroral zone as diffuse patches or arcs (polar cap arcs[), which are generally invisible to the naked eye.

In northern latitudes, the effect is known as the aurora borealis (or the northern lights), named after the Roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas, by Pierre Gassendi in 1621. Auroras seen near the magnetic pole may be high overhead, but from farther away, they illuminate the northern horizon as a greenish glow or sometimes a faint red, as if the Sun were rising from an unusual direction. Discrete aurorae often display magnetic field lines or curtain-like structures, and can change within seconds or glow unchanging for hours, most often in fluorescent green. The aurora borealis most often occurs near the equinoctes. The northern lights have had a number of names throughout history. The Cree call this phenomenon the "Dance of the Spirits". In Europe, in the Middle Ages, the auroras were commonly believed a sign from God.

Aurora Australis or Southernlight

Its southern counterpart, the aurora australis (or the southern lights), has almost identical features to the aurora borealis and changes simultaneously with changes in the northern auroral zone and is visible from high southern latitudes in Antarctica, South America, New Zealand, and Australia. (Source: Wikipedia )

It's a phenomenon which I find wonderful ... such nice colors the night's sky gets when this occurs ... really awesome. So the theme for next week's Tackle It Tuesday will be Aurora Borealis, but you also may use of course Aurora Australis. I am looking forward to your contributions next week. Have fun reading this Preview and let your thoughts go over it ...

See you next week for a new Tackle It Tuesday issue.


PS.: By the way ... as a I already had thought ... Aleph ... was a difficult theme so this Tackle It Tuesday on Aleph will be open for another week. For Tackle It Tuesday Aleph you can contribute your haiku 'till August 27th 11.59 PM. Good Luck everyone.

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